No. A bid is legally binding. If you have the highest bid, you confirm that you have paid the commission and also purchase the car for the amount of your highest bid. You therefore owe the commission in any case (5% of your bid with a minimum of EUR 500 and a maximum of EUR 5,000 including VAT). In addition, the seller can hold you liable if you do not purchase the Car against your offer.
Regardless of any minimum selling price (‘reserve’), the seller always has the right to accept a bid before the close of the auction.